1) To study allotransplantation of the lung in an animal system having immunologic similarities to man where solutions of problems in experimental studies may be applicable to clinical transplantation. 2) To study immunologic relationships between donor and recipient and mechanisms in animals bearing functioning allotransplanted lungs. 3) To study the effects of transplatation on the respiratory and non-respiratory functions of the lung and to scrutinize the reaction to injury of pulmonary tissue in such circumstances. It has been possible to prduce long surviving and functioning orthotopic allotransplants of lungs by preparing a prospective recipient by total body irradiation and bone marrow transplantation from a genetically matched donor. Such animals maintain survival and function of lungs later transferred from the marrow donor to the successfully chimerized irradiated marrow recipients without immunosuppression. It is proposed to study the effects of simultaneous transplantation of marrow and lung in a variety of methods using one or more donors of marrow and lung. The serotypic, genotypic and immunologic factors in such chimeras and their donors will be evaluated. The studies will initially utilize the unique colony of closely bred dogs at Cooperstown in which DL-A homozygous lines are being developed and will later be extended to include mongrel dog populations. The systems developed by these studies may be applicable to cadaver transplantation in man.